/*
 * Copyright (C) 2014 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.common.util.concurrent;

import com.google.caliper.BeforeExperiment;
import com.google.caliper.Benchmark;
import com.google.caliper.Param;
import com.google.caliper.api.VmOptions;
import com.google.common.util.concurrent.AbstractFutureBenchmarks.Facade;
import com.google.common.util.concurrent.AbstractFutureBenchmarks.Impl;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.CancellationException;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

/**
 * A benchmark that times how long it takes to add a given number of
 */
@VmOptions({"-Xms8g", "-Xmx8g"})
public class SingleThreadAbstractFutureBenchmark {
    @Param
    Impl impl;

    private final Exception exception = new Exception();
    private Facade<?> notDoneFuture;

    @BeforeExperiment
    void setUp() throws Exception {
        notDoneFuture = impl.newFacade();
    }

    @Benchmark
    public long timeComplete_Normal(int reps) throws Exception {
        long r = 0;
        List<Facade<Integer>> list = new ArrayList<Facade<Integer>>(reps);
        for (int i = 0; i < reps; i++) {
            final Facade<Integer> localFuture = impl.newFacade();
            list.add(localFuture);
            localFuture.set(i);
        }
        for (int i = 0; i < reps; i++) {
            r += list.get(i).get();
        }
        return r;
    }

    @Benchmark
    public long timeComplete_Failure(int reps) throws Exception {
        long r = 0;
        List<Facade<Integer>> list = new ArrayList<Facade<Integer>>(reps);
        for (int i = 0; i < reps; i++) {
            final Facade<Integer> localFuture = impl.newFacade();
            list.add(localFuture);
            localFuture.setException(exception);
        }
        for (int i = 0; i < reps; i++) {
            Facade<Integer> facade = list.get(i);
            try {
                facade.get();
                r++;
            } catch (ExecutionException e) {
                r += 2;
            }
        }
        return r;
    }

    @Benchmark
    public long timeComplete_Cancel(int reps) throws Exception {
        long r = 0;
        List<Facade<Integer>> list = new ArrayList<Facade<Integer>>(reps);
        for (int i = 0; i < reps; i++) {
            final Facade<Integer> localFuture = impl.newFacade();
            list.add(localFuture);
            localFuture.cancel(false);
        }
        for (int i = 0; i < reps; i++) {
            Facade<Integer> facade = list.get(i);
            try {
                facade.get();
                r++;
            } catch (CancellationException e) {
                r += 2;
            }
        }
        return r;
    }

    @Benchmark
    public long timeGetWith0Timeout(long reps) throws Exception {
        Facade<?> f = notDoneFuture;
        long r = 0;
        for (int i = 0; i < reps; i++) {
            try {
                f.get(0, TimeUnit.SECONDS);
                r += 1;
            } catch (TimeoutException e) {
                r += 2;
            }
        }
        return r;
    }

    @Benchmark
    public long timeGetWithSmallTimeout(long reps) throws Exception {
        Facade<?> f = notDoneFuture;
        long r = 0;
        for (int i = 0; i < reps; i++) {
            try {
                f.get(500, TimeUnit.NANOSECONDS);
                r += 1;
            } catch (TimeoutException e) {
                r += 2;
            }
        }
        return r;
    }
}
